Automatic power cut-off.



F. I. BACKSCHEIDER.

AUTOMATIC POWER CUT-OFF. APPLICATION FILEDAUGI, 1912.

Putened June 12, 1917.

FRANK J. BACKSCHEIDER, F CINCINNATI, OHIO.

LAUTOMATIC POWER CUT-OFF.

accanto.

Specification of Letters' Patent.

VPatented aan@ 12, 1917.

Application alien august 31, 1912. serial No. 718,100. i

To all whom t may concern:

Be it known that I, FRANK J. BACK- soHEIDER, a citizen of the United States, residing in Cincinnati, in the county of Hamilton and State ofOhio, have invented a certain new and useful Improvement in.

. Automatic Power Cut-Offs, of 'which the f ollowing is a full, clear, and exact descriptlon, reference being had to the accompanymg drawings, forming part of this specification.,

My invention relates to a new form of clutch to be used especially in connection with machine tools, but which may also be used on other power driven devices, where it is desired, when the tool or machine is subjected to` an overload, automatically to cause the motor to run free of the stalled device; Vthe clutch, on overloading, ni'oreover, being adapted, where desirable, automatically to disconnect the motor from the source of power supply or to break any link in the transmission, whereby the stalled deviceis disconnected from the power, thus relieving the motor.

In power driven tools and other devices, the i motor, when the toolor other device becomes stalled, is subjected to an overload and is, in consequence, damaged, unless some intermediate means is provided to take care of such overload. -This is usually done, in electrically driven devices, by a fuse, which fuse is burnt out by the overload, thus relieving the motor. The practice of using such fuses, however, results in considerable inconvenience in the matter of replacing burnt out fuses, and it is to relieve the motor from such overloading, without the use of fuses, in the case of electrical devices, that my new clutch is designed, automatically and instantaneously',when the device becomes stalled, to control the power, disconnecting the same either before the motor, or between the motor and the stalled device, thus saving the motor from injury.

The objects of my invention are to provide a clutch by the use ofwhich the pur' poses above outlined will be eiiiciently and inexpensively subserved.

In the `drawings I have shownmy new clutch as applied to tools for grinding and drilling purposes, but it will be understood that the same may be applied to any other power driven tool or device of like orsimilar operative principle, and therefore I do not limit myself to the applications as herein set forth.

In the drawings:

Figure 1 is a longitudinal section of part of a portable electric drill; Y

Fig. 2 is an elevation of the same;

Fig. 3 is an enlarged section of my new clutch as applied to said drill to disconnect the motor from the dynamo;

Fig. 4c is a longitudinal section showing my clutch applied to a grinder;

Fig. 5 is a detail of section;

Fig. 6 is'an elevation of said, clutch;

Fig. is a view of the face of one member of the clutch;

Fig. 8 is an enlarged section of my clutch as applied to the drill in Fig. 1 and adapted to break the transmission.

The numeral l indicates the casing of a the clutch, partly in l l portable electric drill, which maybe of any ordinary type. In said casing the armature 2 is' mounted in the usual manner, and has a shaft 3 whichcarries spur gears 4 and 5,v

the casing. K eyed onto the upper end of said drill spindle is a spur gear 9, which receives motion mediately from the armature shaft, by means of either set of the gearing next described, according as a greater or less rapid movement is desired. Of such intermediate gears there are two sets, one composed of the spur gears l0 and 11, of which the gear 10 is adapted to intermesh with gear 5 on the armature shaft, and gear' 11 to intermesh with gear 9 on the drill spindle; the other set-is composed of gears 12 and 13, of which gear 12 is adapted to intermesh with gear 4 on the armature shaft, and gear 13 with gear 9 on the drill spindle.

`in Fig. l of the drawings for each set of according to the speed desired by turning.

the thumb Wheel 48, which operates an eccentric, in the usual manner, the opposite set being at the same time automatically thrown out.

Coming now more specifically to the. de scription of my new clutch and lone approved method of applying the same to the drill as above described, reference will irst be made to the set oi gearing composed of spur gears 12 and'13, the application of the clutch to each set of intermediate gearing in practice being the same, though I have shown a different mode of application intermediate gears for the purpose of convenient illustration. The spur gear 12 is loosely mounted onthe pintle 14. On the underside of said spur gear is the positive l member of my new clutch, composed of an annular boss 15,.the face of which is undulating, .the raised portions, or teeth, of such undulating surface being radially disposed. On the upper side of the gear 13 is a sleeve 16, large enough to leave a space between said sleeve and the pintle 14 for the receipt of the coil spring 17, which fits around said pintle. Keyed onto the sleeve 16, and adapted to slide vertically thereon, is the'opposed, or 4negative member of my clutch, which, in the construction shown, is composed of the sleeve 18 and the top 19, the said top having an annular boss, corresponding to the boss 15, provided with an undulating surface the teeth of which are adapted to engage the teeth of the boss 15. The spring 17 is interposed between the top 19 and a screw plug 20, said plug being provided with a thumb nut 21 on its ylower end, whereby the plug may be turned and the tension of the spring 17 suitably ad-y justed. lThe tension of said spring will normally keep the teeth of the clutch in engagement, and the said tension is such that the engagement will continue during the normal operation of the tool, and the power will thus be transmitted from the armature shaft, through the lgears 12, 13'and 9 to the drill spindle 6. Should, however, an overload fall on thetool, the same will be communicated backwardly, through the gears -9 and 13 to the negative member of the clutch, where, the engagement of the members not being'absolute, the increased, or abnormal, friction, will cause the clutch to expand against the tension of spring 17 ,the

Y Y mal operation. The arm 42 extends tothe outside of the casing through a slot 45 and is provided with an operating handle 46. The other end of said arm has a finger 47 which is adapted to return the key to its original position where it will engage the gear '5 and properly connect up the transmission, as will be readil apparent, upon the operation of the hand e 46.

To disconnect the motor from the dynamo or other source of power supply, the lower, or negative member of the clutch is provided with an annular collar 22; adapted to bear thereon is a roller 23, mounted in the end of a rod 24, which is slidably mounted in the Wall of the casing 1. Pivotally connected with the free end of said rod is one end yof a rock-bar 25, the rock-bar itself being pivotally mounted between posts on the casing. Pivotally connected .with the other end of the rock-bar is a link 26, the free end of which link is pivotally connected with one` end of a second rock-bar 27; the rockbar 27 being pivotally mounted on the cas- .ing 1.` The other end of the rock-bar 27 is pivotally connected with a second link 28, which link is also pivotally joined to the switch plate 29. Sald switch-plate has a button 30 by means of which the same is operated.

In Figs. 1 and 2 of the drawings I have shown the parts in the positions assumed when the switch plate is in its on position that is, when the current is completed an the motor is in Operation. In said position, as will be seen by reference to Fig. 1, the roller 23 bears on the collar 22. When, now, the tool is subjected to an overload and the positive and negative members of the clutch are cause to expand, or separate, as above described, the collar 22 will force the rod 24 outwardly, and this will cause changes in the ositions of the connected rock-bars and lin rs, shown by broken lines in Fig. 2, the switch-plate being thus thrown, as similarly indicated, to its oii' position, thus breaking the current and relieving the motor of the overload and attendant injury. Asrsoon as the overload is thus removed, the teeth of the clutch will return into engagement, and the roller 23 will be at a slight distance from the collar 22. On throwing the switch to its on position, the roller will again bear on the collar as shown.

my new clutch in a slightly modified form as attached to a grinder.. In'such application, the positive member of the clutch 31 is screwed 1nto a sleeve 32 for purposes of tension adjustment, and locked in proper po sition by a lock-screw 33. The tension spring 34 bearsbetween the' sleeve 32 and a collar 35 secured, by means of a pin 36 to the armature shaft. The positive member of the clutch -is keyed to the armature shaft, but is longitudinally slidable thereon.

above set forth, by the stalling of the tool, K

The emery wheel 37 is suitably secured to a sleeve 38 rotatably mounted on the end of the armature shaft. 'Ehe negative member of the clutch is on said sleeve 38. Slidably mounted in posts on the casing is a rod 39 which carries a roller 40 adapted to bear, when the current is on, against a collar on the sleeve 32. When the clutch is caused to expand, as hereinabove explained, the positive member recedes against the tension of spring 34, forcing back the rod 39 and throwing the switch arm 41 to its 0H position, as shown by broken lines.

In the foregolng I have shown and def scribed the applicationof my new clutch as .adapted to disconnect the motor from the the collar 22 will force downwardly the pivotally mounted arm 42, which carries with it a key 43, as shown in dtted lines in Fig. 8, thus releasing spur gear 5 which is loosely mounted on the armature shaft and permitting the said shaft to run free. The key 43 is slidably mounted in a collar 44 locked to the armature shaft.

The operation of my new clutch will be I apparent from the foregoing description.

The. members of the clutch are normally in engagement, or, in other words, in fixed relative position with reference to' each other, and expand, .or other wise change such relative position,only when subjected to an overload.

I When expanded, the positive member of the clutch is permittedto turn independently'of the negative member thereof, thus relieving the motor of the overload, and, as a further safeguard, the source of power supply may be disconnected from the. motor, or the chain of transmission otherwise severed, by means ofthe change in the relative positions of the members of said clutch, thus discontinuing the operation of the machine until the overf load is removed.

It will be understood that my new clutch is of wide adaptibility and susceptible of considerable modification in details, and Iv do not, therefore, limit myself to the applications and details shown, nor to the 'form of clutch whose members are expansible, as the said members may be caused otherwise n tochange their relative positions with-the same results; and I desire to have it understood that the applications and details as shown are considered only as illustrative of the principles involved, the same being the change in the relative positions of the members of a clutch under an overload, and the control of the power thereby, either by the clutch members being adapted to cause said disconnection of the motor from the source 6-5 of power supplyA or the severance of-the transmission.

/ling the power supplied to said driving member said means being arranged to be. operated by said bearing surface upon the change in the relative position of the members of said clutchf 2. In a device of the character specied, a. clutch vcomprising a driving and a driven,4 member, means normally to hold-said members in .fixed relative position 'with reference `to each other under tension to` transmit power, v the engaging faces of said clutch members being adapted to cause said members to change such relative position under abnormal friction, `means to adjust said tension, an annular bearing surface on one of said clutch members, and means for controlling the'power supplied tb said driving member said means' being arranged to be operated by vsaid bearing surface upon the change in therelative position of thevmembers of said clutch.

3. In a device of the character specified, a O clutch comprising' a driving and a driven member, said members being adapted to be placed in and out of engagement, a spring, said spring being adapted normally to hold i said members in fixed relative position with reference to each other under tension, .to transmit power, the engaging faces of sald members to change such relative' position against the'` tension of said spring 'under abnormal friction, an annular bearing surface on one of said -clutch members, and means for controlling the power supplied to said driving member, said means being ary ranged t'obe operated by said bearmg surface upon the change in the relatlve position` of the members of' said clutch. 4. In a device of the character'specied, a clutch comprising, a driving and adriven member, said members Abeing adapted'to be placed in and out of engagement, a spring, said spring being adapted normally to hold said members in fixed relative position with reference vto each other under tension to transmit power, the engaging faces ofsaid clutch members being adapted to cause said members to change such relative position to be operated by said bearing surface upon against the tension of said spring-under abthe change in the relative position of the normal friction, means to adjust the tension members of said clutch.

,i of said spring, an annular bearing surface FRANK J. BACKSCHEIDER. 5 on one of said clutch members, and means Witnesses: i

for controlling the power supplied to said ARTHUR H. EWALD,

driving member, said 'means being arranged FREDK. J. WENDELU. 

